Pump



.Sept. 13, 1938. w. 1-. bu-NN- $129,828.

PUMP

Filed July 5, 1935 4 Sheets-Sheet l INVENTOR. Mllr'am 7. Dan? Sept. 13, 193 T. DUNN.

4 sneet-sheet 2 Y Filed July 5, 1955 llllillllll-lll\| ll 0 I INVENTOR.

BY xm w I ATTORNEYS.

/44 M21121 Z'Dzlzzn Patented Sept. 13, 1938 UNITED STATES PUMP William T. Dunn,

Chrysler Corporation,

corporation of Delaware 1935, Serial No. 29,777

Application July 5,

2 Claims.

This invention relates to pumps and refers more particularly to improvements in pumps adapted to produce and maintain pressure on a fluid, such as oil, suitable for use in systems of motor vehicle transmission control although my improvements are adaptable to a wide variety of applications. As illustrative of one system of transmission control to which my pump is adaptable, reference is made to the copending applications Serial No. 724,434 filed May 7, 1934 and Serial No. 752,948 filed November 14, 1934.

One object of my invention is to provide an improved pump which will efiiciently and quickly provide a relatively high pressure of the oil, such pressure being maintained preferably without re quiring operation of the pump after the required pressure is maintained.

Further objects of my invention are to provide a pump having improved characteristics of selfregulation in its delivery; improved balance of the parts; a pump capable of long and continuous service, as is required in motor vehicle control, without undue heat generation, noise, wear or failure through other causes; and having improved means preventing the trapping of air in the pumping system.

Another object of my invention is to provide a pump of relative simple construction, having its operating parts compactly arranged for manufacture and assembly at relatively low cost.

In carrying out the foregoing objects, I preferably provide a pump of the swash plate type incorporating an improved'arrangement of control of the swash plate or wabble plate for operating the pistons to produce'and maintain the oil pres sure at the pump delivery without objectionable hunting or fluctuation in the control of the fluid pressure.

Further objects andadvantages of my invention will be apparent from the following detailed description of several embodiments of my inven-- tion, reference being had to the accompanying drawings in which:

Fig. 1 is a sectional elevational view through my pump. 1

Fig. 2 is a sectional plan view along line 2--2 of Fig. 1.

Fig. 3 is a sectional view taken as indicated by the staggered line 3-3 of Fig. 1.

Fig. 3A is a detail sectional view along 3A-3A showing the porting action.

Fig. 3B isa view corresponding to Fig. 3A but showing the parts in a later stage of the porting operation.

Fig. 4 is a view generally similar to Fig. 1 but Detroit, Mich., assignor to Highland Park, Mich., a.

showing a. modified arrangement of springs for operating the pistons.

Fig. 5 is a similar view of a further modification of my invention.

Fig. 6 is a sectional elevational view of another modification of my invention, the view being taken along line 1-1 of Fig. 6.

Fig. 7 is a sectional plan view along line 1-'I of Fig. 6.

Fig. 8 is a'sectional elevationalview of a further embodiment of my invention.

Fig. 9 is a sectional view taken as indicated by line 9-9 of Fig. 8.

Fig. 10 is a view generally similar to Fig. 1 but showing another modification of my improved pump.

Fig. 11 is a sectional elevational view of the stator for the pump shown in Fig. 10.

Fig. 12 is a sectional plan view through the pump of Fig. 10, the section being staggered at the stator as indicated by the line 12-12 of Fig. 11.

Fig. 13 is a fragmentary view in sectional elevation of a portion of trating a further modified arrangement of piston operating springs. I

Fig. 14 is a sectional elevational view of an other modification of my pump.

Fig. 15 is a sectional plan view |5-l5 of Fig. 14.

Fig. 16 is a detail sectional view along line l6-l6 of Fig. 15. I

Fig. 17 is a diagrammatic view of the pump stator and rotor ports during cut-off of fluid pressure,delivery.

'Referring to Figs. 1 to 3 the pump illustrated in this embodiment of my invention comprises a suitable supporting structure A which may be a portion of amotor vehicle transmission casing formed with the generally cylindrical portion 20 thereof adapted to house the cylindrical pump rotor 13.

Rotor B comprises a and an upper body 22 taken along line lower enlarged body 2| secured together by fasteners 23. The upper body 22 is suitably driven by a gear 24 connected by interlocked teeth 25 with the upper end of body 22, the gear being rotatably journalled by an anti-friction bearing 26 mounted adjacent the-upper end of a stator C. The upper and lower ends of the stator are respectively centered and fixed within the support conduit 21 and the cylindrical boss 28 of a casting 29 which houses the lower parts of the pump mechanism, this casting being secured to support A by fasteners 30.

my Fig. 1 pump but illus- 'modating a spring 36 acting between the upper body 22 and the piston for yieldingly urging the piston downwardly to maintain the lower rounded. end 31 thereof in contact with the upper element or ring 36 of a swash plate D. The lower element 39 rotatably supports the upper ring by the anti-friction bearing 390 and is rigidly mounted on spaced arms40 secured to a shaft 4| journalled at its opposite ends at 42, 43 in cast ing 29 for pivotal movement by an arm or lever 44 fixed to shaft 4i and thus movable with arms 40 as will presently be apparent.

Radiating inwardly from the upper ends of each cylinder 33 is a slot-like conduit 45 providing an inlet for the fluid to each cylinder. Stator C has an axial bore 46 for supplying the fluid upwardly from a reservoir in support A, the fluid level being well above Opening 47 to deliver the oil through transverse stator passage 48 communicating with bore 46. The latter bore terminates at 49 just above the radially extending outwardly flaring delivery passage 50.

The upper body 22 has its under face formed with circumferentially spaced radially extending milled slots forming pressure delivery passages between the respective cylinders 33 and the stator. The stator has an upwardly ex-' tending delivery bore 52 which terminates just below a second radially extending outwardly flaring passage 53 which extends 180 from passage 50. The upper end of bore 52 delivers fluid to conduit 54 in the support 21 and is suitably conducted to the points of use of the fluid under pressure produced by the pump.

The arm 44 carries an adjustable abutment screw 55 pivotally seating spring abutment 56, a spring assembly 51, 58 acting between casing abutment 59 andabutment 56 tending to yieldingly tilt the plate D as shown in Fig. 1. The spring assembly determines the oil pressure maintained by the pump as will be presently apparent.

In operation of the pump in Figs. 1 to 3 as thus far described, the bodies 2|, 22 are rotated as a unit by drive gear 24, pistons 34 -being reciprocated by swash plate D and springs 36. As the pistons pass passage 50 they are moving downwardly and thereby drawing oil from the reservoir to bore 46 for delivery through passage 50 and passages 45 then in communication therewith; the remaining pistons moving up-v wardly and delivering oil under pressure from their cylinders 33 through the associated passages 5| and thence to the passage 53 and conduit 52.

The intake and delivery through conduits 46 and 52 is thus continuous and the pressure rapidly builds up to the desired value determined by the strength of spring assembly 51, 58 and theratio of the leverage of arms 44 and 40 about pivot 4|.

When the delivery pressure tends to exceed. the

'desired value, which may run in the neighborhood of 500 pounds per square inch for transmission control systems, the delivery pressure acting through the upwardly reciprocating pistons 34 causes plate D to level off about pivot 4| further compressing springs 51, 58 and thereby reducing or eliminating reciprocating movements of the pistons depending on the rate of use of the oil pressure or rate of .fall in such pressure.

I The plate D will thus assume an angle depend-' ing on .the pumping requirements and normally the pump, after producing the desired pressure, will become inoperative insofar as reciprocation of the pistons is concerned until such time as the pressure falls for any reason. With the pump operating at maximum delivery capacity, pistons 35 closely approach the upper body 22, thereby insuring against entry-of air into the system. The delivery pressure may be readily varied by adjusting the tension of springs 51, 58 at the abutment 55.

The passages 45, 5| are preferably milled saw kerfs for low cost manufacture, these pairsof passages being preferably vertically communicating whereby. passages 45. function alternately both as delivery and inlet passages for cylinders 33.

As a further feature of my invention, I have provided means for balancing the side thrust between stator C and body 22 occasioned by the radial high pressure passage 53. Thus, above passage 53 and extending 180 therefrom is a further similar passage 6'0 between conduit 52 and the inner walls of body 22, it being apparent that in this manner the side thrusts are balanced out. In the absence of my pressure balancing port, the stator C and body 22 are relatively displaced by the fluid pressure giving rise to leakage between these parts. This relative displacement exposes more area of these parts to the high pressure fluid which in turn produces more separation and more leakage.

4 Above the pressure thrust balancing passage 60, the stator is formed with a series of axially spaced narrow circular grooves 6| forming a labyrinth seal against the escape of oil outwardly between body 22 and the stator.

If desired, a cylindrical shield 39| may be supported between casing parts 20 and 25 to surround bodies 2| and 22 to prevent undue foaming and splashing of any. oil thrown from the pump bodies. 1

By reason of the arrangement of fluid circulation through stator 0 whereby the oil enters at the lower end and is delivered at the upper end, I have provided a uniflow action of the oil, preventing air hammer, air trapping, and air pounding. It is, of course, highly desirable to provide noiseless pump operation and my pump has improved characteristics, of quietness of operation. Furthermore, since the pistons are not reciprocating the majority of the time, the life of the pump is materially increased over prior known types of pumps adaptable to the uses suggested hereinabove.

In order to limit upward movement of pistons 34 under the action of springs 51, 53 and plate D and to also adjustably vary themaximum stroke of the pistons with accompanying variation in the pump discharge, I have provided the element 39 with a second lever arm 392 which extends oppositely from arm 44 but integral therewith. Arm 392 carries an adjustable set screw 393 which strikes a bracket stop 394 depending from support A. The set screw provides the means for adjusting the stroke of the pump as aforesaid.

With the rotation ofbody members 2|, 22 as indicated by the arrow in Fig. 3 the pistons 34 progressively move upward, pumping oil, for those cylinders which have their discharge slots 5| communicating with the stator pressure chamber 53. When each of the slots 5| reaches the end of chamber 53, the pressure discharge my invention just so through such slot ceases at a point in the rotation of body 2| where the piston is approximately at its uppermost limit of movement. The piston associated'with such slot is then momentarily sealed from communication with stator chambers 53 and 55 by the stator walls between these chambers. Continued rotation progressively brings passages 45 into communication with stator intake passage 5|], the pistons moving inwardly. Slots 5| are closed on from communication with chamber 53 during the time slots 45, which are associated with such closed off slots 5|, are open to the intake chamber 5|]. Approximately half of the cylinders are continuously operating for intake while approximately half are continuously operating for pressure discharge of the fluid, assuming of course that the plate D is not levelled off.

I have further provided means for preventing what is known as a wire drawing efiect in fluid pumps. This effect is in the nature of a knock or hydraulic hammer resulting from too abruptly cutting off the pump fluid pressure delivery. To a lesser extent these objectionable noises often occur at other points in the cycle of pump operation such as at intake cut-off for each cylinder. To overcome these objectionable noises, I have provided a porting structure having a very gradual actioh and a typical arrangement will be described in reference to the pressure delivery cut-off.

It will be noted'from Figs. 1 and 3 that the generally vertically extending walls of chambers 50 and 53 are curved. This produces a desired curved edge at the ends of these chambers where the stator controls porting events with passages 45 and 5|. For convenience the said curving is carried across the chambers 50 and 53 although the controlling edges alone provide the desired functions being now considered. Furthermore other edges than curved may be employed within keeping of the broader teachings of this phase of long as a gradual porting action is obtained.

In Fig. 3A I have illustrated a passage 5| approaching cut-off from pressure chamber 53, the piston associated with such passage 5| nearing the top of its stroke. In Fig. 3B, the same passage has rotated or moved from the Fig. 3A position and is just completing the pressure cut-ofi. This cut-off action is very gradual as the trailing edge of passage 5| progressively eclipses the curved edge of chamber 5|. A similar condition is preferably provided at the other porting events of the pumping cycle as will be readily understood.

In the Fig. 4 embodiment of my invention, most of the parts are identical to those in Fig. 1 as indicated by the same reference'numerals. However, in Fig. 4 the pistons 34 are solid and springs 36 associated therewith are located above the pistons, the body 22 being enlarged to provide the spring receiving pockets 62.

Referring to the embodiment of my invention illustrated in Fig. 5, the stator C has its intake bore 46 offset from the stator axis containing delivery bore 52*. the inner ends of these bores overlapping axially and respectively communicating with radial outwardly flaring intake and delivery passages 50 and 53 respectively. The latter passages respectively communicate through a series of circumferentially spaced conduits 45 and 5| with the similarly arranged cylinders 33 having pistons 34 associated therewith.

In Fig. 5 I have provided a single common 3G acts.

able centrally spring 3|; surrounding the body 2| for urging To this end the pistons 3 4 are joined, for relative movement nevertheless, by a ring 63 passing holes in through the lower ends of the pistons. Seating on this ring and loosely receiving the pistons therethrough is a plate 64 on which spring The upper end of the spring abuts the outer portion of a frusto conical ring 65 which seats on a similar face of body 33, through an intermediate gasket 56, for closing the upper ends of cylinders 33*. The cylinders may thus be formed completely through body 33 which is a unitary structure driven as before by a gear 24*.

The ring 65 has an upper cylindrical portion fitted to the cylindrical part of body 2| above passages 53 and 53', a threaded nut 61 holding the ring 65 in position. I

The stator C has its lower end'formed with a plate 53 formed with a supporting shaft 4| on one side of other side. Plate D pivots on shaft 4| and has a lever extension 44 provided with forked ends 10 receiving therebetween a cup 1| having a lever flange 12 against which the lever ends 10 act. The boss threadedly receives the upstanding pin 13 which passes through the upper end closure 14 of cup 1| and threadedly receives stop washer 15 and nut 16 adapted to adjustably limit upper movement of cup 1|. This cup is urged upwardly by a spring 51 centered by boss 69 and surrounding pin 13. By adjusting the'nut 16 it will be apparent that the maximum. upward movement of pistons 34 is adjustably controlled as well as the pump stroke in a manner similar to the adjustment of the set screw 393 in the Fig. 1 embodiment.

The operation of the Fig. 5 embodiment is substantially similar to the Fig. 1 arrangement. When the plate D levels off under the pressure developed by pistons 34, the lever ends 10 depress cup 1| against spring 51, it being noted that in this instance the fulcrum 4| of the plate D is on the opposite side of stator C from the spring 51 The oil is suppliedv to conduit 46* through inlet passage 48* as before.

Referring now to theFig. 6 embodiment of my invention, the stator C surrounds the rotatdisposed body 2| driven by gear 24. This body is formed with downwardly opening cylinders 33 receiving portions 34 urged by springs 36 against the plate D pivotally supported at 4| between the vertical axis 11 of the plate lever portion 44. The plate in this instance has a hardened wear resisting insert 18 slidably engaging the pistons 34. The stator is formed with the diametrically opposite fluid inlet and discharge passages 50 and 53 respectively, these passages being alternately open to cylinders 33, as body 2 rotates, through the radial passages 45. The fluid intake to passage from the fluid reservoir is provided by a vertical conduit 46 provided in the stator while the pressure discharge in this instance .is directed downwardly through conduit 52.

the stator and a boss 69 on the.

all of the pistons against the swash plate D The discharge passage 53 has an extension 19 of passage 53 and having its lower end engaging rise in the fluid delivery pressure.

lever 44. By reason of the offset between axis 11 and pivot shaft H it will be apparent that a majority of the pistons 34 will act to urge plate D to its inclined position as illustrated in Fig. 6. The pressure 'rise, above a predetermined amount depending on the diameter of plunger 85, strength of springs 36, length of lever 44 and other factors, will act through the plunger to level off the swash plate as before described.

In this embodiment of my invention, the swash plate is arranged so that in leveling off toward its horizontal position the pistons 34 move upwardly (rather than downwardly as in Figs. 1, 4 and 5). This has the advantage of positioning the pistons, when levelled off, at or very close to the cylinder closing walls 86 where the pistons normally lie at the tops of their working strokes.

Thus the volume of oil trapped above the pistons is a minimum resulting in reduced air trapping and noise. Any leakage including fluid pressure loss due to porting as the pump body rotates at the level off condition, results in the plate D adjusting itself for a small movement of pistons 34 and this sometimes produces objectionable noises unless the clearance space above the pistons is maintained relatively small. The circular form of passages 45 provides gradual eclipsing with the edges of passages 50 and 53 to obtain the advantages set forth in connection with Figs. 3A and 3B.

Referring to the embodiment illustrated in Figs. 8 and 9 I have illustrated my pump rotatably about a horizontal axis instead of a vertical axis. The transmission drive shaft 81 passes freely through the rotatable body 2N driven as before through coupling 25 this body having horizontally disposed cylinders 33 accommodating pistons 34 the intake and delivery passages l5 communicating alternately with the intake and delivery passages 5i! and 53 of stator C. The body M may be driven with shaft 81 but is preferably driven separately at a higher speed from shaft 81 or other power source so that when the motor vehicle idles or drives slowly, the pump will be rotated sufliciently fast to build up and maintain the desired oilpressure. Oneof the ends of the pistons are loosely tied by a ring 63 (as in Fig. 5), the pistons acting against ring 33 of plate D The latter plate comprises bearing 390 and lower ring 38 having a lever extension 44. The plate ass'emblyp is pivotally supported by ears 394 projecting from plate 39 these ears being pivotally supported at 4| from the casing structure. 1

Only every third piston 34 has a spring 36 urging the piston outwardly. However, the pistons are tied together by ringj3 as aforesaid so that movement of all pisto ns in following the inclination of the swash plate is assured. Plate D is pivoted at the horizontal axis of the pump and the normal tendency for the plate to tilt as in Fig. 8 is produced by a spring 5! opposed by a plate controlling plunger exposed at its inner end to the discharge passage 53 The plunger functions similarly to plunger 85 of Fig. 6 in leveling oif plate D in response to abnormal In Fig. 8 it will be noted that the fluid enters chamber 50 through intake 88 and leaves chamber 53 through outlet 89, the fluid travelling transversely to the horizontal pump axis along a substantially vertical plane, the delivery of the cylinders prererably being at the highest points inwardly of the cylinders, as before, to prevent airtrapping. Obviously, if desired, the pump may be positioned for operation on avertical axis of rotation instead of horizontal.

Referring to Figs. 10 to 12, I have illustrated a further embodiment of my invention closely similar to the Fig. 1 embodiment (as indicated by the use 'of many similar reference characters) but differing therefrom primarily in the manner of balancing the stator and pump body against relative displacements resulting from the pressure of the fluid.

The oil is drawn into the stator C through inlets 48 to bore 46 thence to the inlet chamber 50? for admission to cylinders 33 through passage slots 45. The cylinders deliver the oil under pressure to the chamber 53 whence the oil passes through delivery bore 52 to its points of use.

One feature of my present arrangement resides in the provision of a compact structure occupying less space than usual together with less pump Weight and cost by overlapping the chambers 50 and 53 in the direction of the axis of stator C as is clearly shown in Figs. 10 and 11.

As another feature of this embodiment of my invention, the pressure balance for the stator and rotating bodies 2| and 22 is divided attwo points so that the opposing or counteracting pressure acts below the chamber 53 as well as thereabove as in Fig. 1 at chamber 60. Thus, pressure balancing stator chambers 66 and 60 respectively communicate by stator passages 90, 9| with bore 52 and chamber 53*. In this manner the stator is relieved of any tilting tendency since the balancing forces do not produce a couple as in Fig. 1. At the same time separating tendency between the stator and rotating pump bodies with resulting leakage and binding is prevented.

From Fig. 12 it will be noted that the pistons reach top dead center just prior to cut-off of fluid pressure delivery fromsuccessive passages 5|. This condition is illustrated for the uppermost cylinder in Fig. 12. In this manner I prevent carrying over a pressure in the passages 5| to the intake passage 50 and allowing for complete evacuation without producing hydraulic hammer noises and shocks. A slight amount of vacumn is created in each passage 5| and associated cylinder between pressure cut-01f and intake thereby producing a rapid inflow of fluid at the start ofthe intake cycle for each passage 5|. In the same manner the arrangement is such that for intake cut ofi each piston reaches bottom dead center just before cut-ofl' takes place, providing for more efficient intake an general pumping efliciency.

Referring to' Fig. 13, I have illustrated only a portion of the pump structure intended to be identical to that of Fig. 1 excepting that the pistons 34 have an individual spring 36 surrounding each piston instead of being located within each piston as in Fig. 1. Each spring acts between an abutment 92 carried by a piston and a relatively fixed abutment provided by cylindrical recess 93 in the rotatable body 2|. Obviously any of my other embodiments may I have the pistons thereof provided with exterior other embodiments.

The stator C draws oil through bore 46 which opens to intake chamber 53' passes oil under pressure through bore 52' and thence through cates with the of the fixed casing 21 The pistons 34, swash plate D pivotally mounted at M with lever M "i=1 oil pressure operated leveling off plunger s. -'--r.--: as described in connection with parts corresponding thereto in Fig. 6. However, in Fig. 14 the plunger bore 8| communibore 54, a pressure relief valve 82 being provided thereabove. In order to prevent too sudden movements of control plunger 85 and plate D, the bore 8| contains a fixed baflle 94 having a restricting orifice 95. The baffle acts as a dash pot to check undesirable fluctuations and sudden movements of the swash plate.

I have also provided a further improved porting arrangement and construction for obtaining improved pumping efficiency and quietness of operation.

Each of the chambers ill) and 53 has at least one controlling edge thereof, such as the intake cut-off and the pressure cut-off edges respectively, constructed for improved operation with the cylinder passages 45. In Figs. 16 and 17 I have illustrated this arrangement in connection with the typical passage 53 This passage is generally rectangular in section except in the region adjacent the discharge controlling edge where'the'inner wall of the passage has a curved groove 96 which terminates outwardly in a rather sharp pointed generally elliptical edge as shown in Fig. 1'7. As the circular port of passage 45 sweeps across the edge 96 as the body 2| rotates, as indicated by the dotted line in Fig. 17, the discharge of fluid from passage 45 to chamber 53 is very gradually cut off.

noted that when my piston is at its highest point, the rotor port Mi has just passed the stator port edge 96', the discharge passage 45 being carried as far as possible while pressure is being built up by the piston and while passage 45 is open to chamber 53 This provides relatively great pump efliciency and prevents carrying over a pressure of an increasing character, in any cylinder, to the intake chamber 50.

'. The inner ends of passages than the height of the groove controlling outer edge so that leakage willnot occur to any undesirable extent between adjacent ports 45 at the region of final fluid discharge to chamber 5i! and at the same time to obtain as large a number of ports and cylinders as possible in the rotor. I

What I claim is: 1

1. In a fluid pump, a substantially vertically disposed stator having axial fluid inlet and delivery conduits respectively formed in the oppoposition inclined with respect 45 which form circular ports preferably have a diameter smaller 96 at the port site ends thereof, said stator inlet end projecting into a reservoir containing fluid to be pumped, a rotor surrounding said stator coaxially therewith, said rotor having a plurality of cylinders spaced around said axis, pistons in said cylinders respectively, a pivotally supported wabble plate surrounding sa'd stator in engagement with one end of said pistons, said rotor having a plurality of fluid conducting passages respectively opening to said cylinders, said stator having inlet and delivery ports respectively come municating with said stator inlet and delivery conduits, said stator inlet and delivery ports being respectively positioned to successively register with a plurality of said rotor passages during rotation of said rotor, said statorhaving afluid conducting passage communicating at oneend thereof with said fluid delivery conduit and having its other end disposed to subject said rotor to the pressure of fluid in said passage, means yieldably urging swinging movement of said wabble plate about its pivotal support toward a to a plane perpendicular to said axis, and means responsive to the pressure of the fluid delivered by said pistons for moving said wabble plate in opposition to said yielding means.

2. In a fluid pump, a stationary structure having fluid inlet and delivery passages, a rotary structure formed with a plurality of cylinders extending in the direction of the axis of rotation and spaced circumferentially thereof, a piston reciprocating in each of said cylinders, means for conducting fluid from said inlet passage to said cylinders in response to movement of said pistons in one direction of reciprocatory movement thereof and for delivering fluid under pressure from said cylinders to said delivery passage in response to movement of said pistons in their other direction of reciprocatory movement, a wabble plate structure controlling movement of said pistons, wabble plate adjusting means comprising a lever arm, common means for pivotally mounting said wabble plate structure and said lever, yielding means acting on said lever arm for imparting swinging movement to said wabble platestructure, means carried by said lever arm and acting on said yielding means for adjustably conditioning the latter for predetermining the fluid pressure maintained by said pump, means including a second lever arm operably associated with said first mentioned lever arm for limiting upward movement of said pistons under the action of said yielding means, and adjustable means acting on said second lever arm for varying the upward movement of said pistons.

WILLIAM T. DUNN. 

